It has long been recognized that the use of lighter-than-air balloons or other aerostats for transporting loads such as logs in inaccessible or rugged areas would be extremely beneficial. Several attempts have been made to develop efficient balloon systems for transporting loads.
Stewart, U.S. Pat. No. 3,270,895, for instance, discloses a balloon yarding system which uses a combination of static lift and aerodynamic lift to move logs from a pickup site to a discharge site. The attitude of the balloon is controlled to increase or decrease the aerodynamic lift to assist the static lift of the balloon. A conventional yarder retracts or extends a main line and a haul-back line to move the balloon in a straight line.
Fenn. et al., U.S. Pat. 3,448,864, discloses a two-line balloon logging system wherein the main line is controlled by a first winch and the haul-back line is controlled by a second winch. A lift line, when lowered, adjusts the angle of attack of a balloon to increase the lift capacity. The angle of attack of the balloon is controlled by the amount of load applied to the balloon.
Langford, U.S. Pat. No. 3,865,251, discloses a balloon yarding system for transporting logs in a straight line which utilizes a single continuous cable for out haul, in haul, and altitude of the balloon. Selective extension or retraction of the cable causes the balloon to traverse a straight line and to vary in altitude.
Chipper, et al., U.S. Pat. No. 4,055,316, recognizes the problem of keeping balloon control lines above and away from any obstacles which could snag the lines. A lifting balloon is provided for lifting a load. A pair of winches is provided, one on each end of a control cable, for moving the lifting balloon from a loading site to a discharge site. A plurality of auxiliary balloons are provided to keep the cables above any obstacles.
Each of the above attempts at balloon yarding was adequate for its intended purposes but several limitations and problems still exist. The above systems could only operate in a straight line within a limited area. To change the area or path of coverage, either a winch or turning blocks for a yarder, needed to be relocated. This is extremely difficult in rugged terrain.
A need, therefore, exists for a balloon transportation and yarding system which can cover a wide area without the need of relocating essential components. A need also exists to insure that all control and attachment lines are always clear of any obstacles on the terrain. A further need exists for an efficient control of the balloon within its area of travel. Finally, a need exists for a balloon transportation system that fulfills the foregoing needs simply and safely.